Please note. Patriot and Supernovachucks in 33mm x 3.5 thread and 1,1/2" have to be specially made with the thread cut in the body, as there is not enough room to take an insert. The Patriot 1,1/2&quot version is dual threaded left and right so it can go on either end of a Harrison Graduate spindle. Unthreaded chucks are available from suppliers if you can arrange your own machining. The thread in the Patriot and Supernova where the insert fits is 38mm x 3mm. Robert Sorby make "Exerts" to adapt chucks to fit large threads such as Viceroy 1.5 inch x 8 t.p.i.

The above list is
only a guide and lathe makers vary the thread they use from time to time.
The Peter Child shop is now closed and the information is left here in the hope it will be useful

Hint on measuring your thread size
It is often possible to guess at common thread sizes with an ordinary ruler. Examples are :-
1 inch x 8 tpi. The outside diameter of the thread is a tiny bit below 1 inch. 1/8 inch divisions on the ruler will exactly line up with the peaks of the thread.

3/4 inch x 16 tpi. The outside diameter of the thread is a tiny bit below 3/4 inch. 1/16 inch divisions on the ruler will exactly line up with the peaks of the thread.

24mm x 3mm pitch. The outside diameter of the thread is a tiny bit below 24mm. Every third 1mm division on the ruler will exactly line up with the peaks of the thread.
And so on.

Some threads described as "Whitworth" have the 55 degree thread form of the standard Whitworth threads but have non-standard tpi which can confuse!